Relation of early improvement in coronary flow reserve to late recovery of left ventricular function after β-blocker therapy in patients with idiopathic dilated cardiomyopathy

Background: β-Blocker therapy reverses left ventricular (LV) remodeling in patients with idiopathic dilated cardiomyopathy (IDC). Improvement in coronary circulation by β-blocker could play a role in these circumstances. This study investigated the relationship between change in coronary flow reserve (CFR), as a marker of coronary circulation, and subsequent improvement in LV ejection fraction (LVEF) at follow-up during carvedilol therapy in patients with IDC. Methods: Eighteen patients with IDC underwent CFR measurements by transthoracic Doppler echocardiography at baseline and after 1 month of treatment with carvedilol. A follow-up echocardiographic assessment of LVEF was done at 12 ± 6 months of treatment. The patients were classified by the degree of improvement in LVEF in the follow-up study, as group A (LVEF change ≥10%) and group B (LVEF change <10%). Results: Although there was no significant difference in CFR between the 2 groups at baseline, CFR was significantly higher in group A than in group B at 1 month of therapy (3.7 ± 0.5 vs 2.5 ± 0.9; P < .01). Coronary flow reserve change after 1 month was significantly greater in group A than in group B (1.3 ± 0.6 vs 0.4 ± 0.5; P < .01). Logistic regression analysis revealed that CFR change predicted a significant improvement in LVEF at follow-up (P < .05). Furthermore, a significant correlation was found between the change in CFR after 1 month and that in LVEF on follow-up (r = 0.65, P < .01). Conclusions: This study demonstrated that early change in CFR is associated with subsequent improvement in LVEF, suggesting the potential predictive value of coronary circulation for subsequent LV reverse remodeling after β-blocker therapy in patients with IDC.